Posted
by
Hemos
on Monday January 22, 2001 @12:49PM
from the look-pnub-in-too-many-places dept.

LtFiend writes "Evidently, some astronomers believe that SETI is searching the skies for the wrong type of signal. This new telescope built by Harvard will search for laser light and can detect pulses " as short as a billionth of a second." Looks like we'll need a new version of SETI at home so we can help with
this one."

The media tends to like controversy because it sells better. None of the SETI researchers has claimed that "SETI is searching the skies for the wrong type of signal". Horowitz, who is building this all-sky optical search, has been doing microwave SETI for decades. He is the genius behind the META and BETA searches.
Just because people are now exploring the optical regime does not make microwaves a less likely place to find an alien signal. All it means is that the researchers are trying something new.
Why try something new? Because our technology has advanced to a point where they can. Also because the researchers get bored with old ways and want to try something different. It can get pretty monotonous doing the same kind of thing year after year with no positive results.

I'd based 20,000 years on the assumption that there are things like planet-scale distasters that a race cannot avoid - meteors from space, killer radiation from local stars going nova - in addition to the fact that based on even primitive life on earth, there would always appear to be a "only the strong survive" drive to survival, and whether that means that two warring tribes of the same race wipe each other out with sticks or nuclear weapons, it still suggests that there will always a possibility for self-destruction of one's race.

Now certainly I may be way low -- it HAS been 65 million years from the last major planetary event that caused a mass extinction, but even if you start pushing the timeframe of humans up to 100,000 or a million years, you are still talking about blinks of an eye relative to the estimated age of the universe. But again, the key thing is that one takes the assumption that races might die out -- if you assume otherwise, then yes, as the age of the universe increases, the chance for finding life should increase also.

With the only senses that we can trust: sight and touch. We have to GO and find these things, and that means space exploration. In the 2nd Millenium and the beginning of the 3rd, this is certainly not a big priority, but maybe by the year 2500, we'll have the technology that will allow a reasonable way to explore nearby star systems and look for signs of life, whether active or not.

I'm not saying SETI should be shut down -- because there is the possiblity we'll get something and all these arguements are moot. But it's more just looking at the big picture and realizing that we might just be shooting pot shots into space.

It wouldn't bend around them, radio waves would pass through them. Radio waves tend to be too low of an energy to be picked up by atoms to induce electrion jumps, so they'll pass through objects with no problem (that's why you can get radio and attenna TV inside a house).. although with a planetary-sized body there will be some distortion. Light waves, on the other hand, are easily picked up by most metallic substances, and therefore will be absorbed.

All I'm saying is that the stars in the local area of the Milky Way were probably all created within a few million years of each other , collesing from the same gas cloud; a few million years again is tiny on the cosmic scale.

And the next step up from galaxies is "galactic cluster", where again it's suggested there's some central object which several galaxies tend to gather about, but certainly not as strong that keeps planets in orbit or stars in orbit.

I rewatched 'Contact' this weekend, and it gets me to thinking on what chance we have as the human race (as in, over the next several millenia) will have in encountering a non-extinct, developed alien race. Humankind has only been around on the order of 10,000 years, and we'll probably have at least that coming in the future, but 20,000 years on the cosmic scale is a blink of the eye. Assuming that other races have similar 'lifespans', it may be easy enough to miss them because we started too late or too early. For example, we know that there's a narrow band where liquid water could exist on a planet based on our sun; what if earth's orbit was a few thousand kilometers closer: would life have developed a bit faster, and maybe humankind would have rose out 100,000 years earlier? Or mnay it would have been slower and we wouldn't be talking about this for yet another 100,000 years. And that's just earth we're talking about -- in any other solar system you'd have to worry about the same facts.

I think the only thing we can safely say about extraterrestial life is that if we are going to find any with sufficient technological progress within the 'lifetime' of humankind, it will have to be from a very small cluster of stars near us, which might have been formed near the same time after the big bang, such that planets capable of supporting life would have all started the evolution timer at the same point. But again, that rate of evolution is so different that the chances of us seeing one another would be very very high.

What I think we should focus on more (and it would be hard to say if we will be able to) is to look for the evidence of early life (single celled protozoa), or evidence of a race gone dorment, on other planets in the nearby cluster.
Finding such would at least tell us that the development of life was not a chance happenstance on Earth.

Anyone remember a comic book from the late '80's called "Stray Toasters"? It was about a demon that took a vacation from Hell in New York, and started messing with some really deranged people, lawyers, etc. "Toasters" were demons. (well, it's what they do, right? stick ya with a pitchfork, and hold you over the flames. . . )

5,000,000 BC
An alien race has evolved intelligence, develops technology and decides to attemtp to contact other intelligent beings using broadcast radio signals.
4,000,000 BC
Another alien race contacts the first race.
2,000,000 BC
These two races have build a huge trade confederation, and have discovered several other races. Humanity is not beyond their frontier, but has not been physically detected. At this point, humans are still spearing wooly mammoths. Several other pre-technological races have been discovered and were nurtured until maturity, when they could join the confederation.
1,000,000 BC
Huge interstallar war wipes out most civilization.
100 BC
On one planet where civilization survives, a new, conservative, isolationist government comes into power. They cease all contact with alien planets, they cease broadcasting.
1900 AD
Humanity has developed into an intelligent, industrialized society on the verge of technological advancement.
2000 AD
Humanity has been listening to the heavens and broadcasting signals, in hopes of contacting an alien race.
2100 AD
A violent civil war on Earth resulted from a combination of depletion of natural resources, destruction of the environment, and massive copy-protection schemes. Humanity is nuked back to the stone age. Both consumers AND business loses. Global warming melts the ice caps, and floods the continents killing all surviors.
2501 AD
A violent civil war on the alien planet unseats the traditionally conservative isolationist government. The new regime soon resumes broadcasting and listening for signals.
2,000,000 AD
Alien archeologists find evidence of a past civilization on a small planet, which was located just a few light years away from one of the main trade arteries of the old confederation. The surface is covered with ice, beneath the crust lie ruined cities, and craters, evidence of a massive nuclear conflict. Scientists are still unable to decode the contents of data disks recovered from one of the sites; almost as if the data were purposely scrambled. No big loss, since it was a copy of Titanic on DVD.

Yeah, there will be some beam divergence, and,
as another poster pointed out, if you have a
large distance, the beam size can be pretty big.
But in astronomical terms, I don't think the beam
could get that big before extinction would
would completely absorb the beam, or reduce the
signal strength to such a level that it's pretty
near impossible to work with.

Alternatively, if you were to go down into the
IR, you'd at least have a better chance of the
signal getting through (less extinction in the IR), but you still have the problem with the beam size being pretty tight, as well as the need to be looking at the right place at the right milisecond.

I'm afraid you haven't convinced me. Extinction may not be a problem between the sender
and the intended reciever, but for an interloper
such as us? When we're not exactly sure what is
we're looking for? When the pulse may be compressed into something unrecognizable? Not good. As for the IR, see my other post about
that. Yes, looking in the IR is a much better choice.

As for 2, that is not a major error, but I did not explicitly state my entire reasoning, so
let's think about it for a second. Yes, the beam
will spread, and as it spreads, you lose power.
Our ET's are going to want to use as little amount
of power as possible, hence the beam will more likely than not, be as focused as possible.
Unless they are sending an "is there anyone out
there" message, which I would put odds of 50-50
on that right there.

Finally, even if the beam width is larger than
the size of the solar system, is that really significant? I would argue that
it is not. Catching gamma bursts will be easier,
they are at least going to be more frequent...

I wouldn't be worried about posting this as an AC,
That's a really interesting idea. I'm not so sure
I buy the idea that you'll be able to get a usable
signal out of the scattered light, it's possible
I suppose, but I don't think it would be easy.

You're going to pick up a lot of noise
with that technique. Not to mention the loss of
signal strength, assuming you can detect the signal at all.

While such a thing may be technically possible,
these guys seem to be glossing over some very big
problems.

1. Optical communication across interstellar distances is going to suffer from severe extinction (signal absorption by intervening dust). Even if you can generate a laser pulse
brighter than the sun, interstellar extinction is
a big problem to overcome.

2. A laser beam is very tightly confined, and
would have to be aimed very precisely in order to
"hit" it's target. The probabability that the Earth
would just happen to cross one of these "lines of
communication" is incredibly small.

So it seems to me that while optical commmunications could work in principal, radio is
going to be much easier to work with, since
you don't have to worry about extinction or pointing problems as much.

Homo erectus is currently thought to have arisen about 1.8 million years ago, and existed until about 400,000 years ago. Homo sapiens neanderthalensis, though possibly not a direct ancestor of "modern man," is very similar to our species and probably lived from about 300,000 years ago to about 30,000 years ago. You and I, homo sapiens sapiens, which I assume to be your "humankind," are thought to have appeared about 120,000 years ago.

>My assumption is that the intelligent species out there aren't advertising their presence.

Interesting assumption. Too bad the only example we can test it against in the universe (ie, humans) violates it.

Violates it? Barely. How far are our radio emissions distinguishable from background noise? I thought it was only a few dozen light years. And IIRC, according to the recent Scientific American article on SETI a couple months back, although we could send directed communications for thousands of light years with an Arecibo, our current searches wouldn't detect an 20th century level civilization at any distance.

We make no attempt to hide our presence. It's pretty conceivable to me that other species could make the same "mistake".

Unless it really is a mistake. It could be that a sizable minority of species in the galaxy is both malevolent (in the sense that they would destroy weaker, expanding technological civilizations in order to avoid future threats to their own existance), yet hiding their presence (perhaps because they fear a more powerful, yet similarly hiding civilization). In such a scenario, any emerging technical civilization which did not adopt a hiding strategy would be toast before it was finished colonizing it's own solar system.

There's a cute Fermi's Paradox discussion on sci.space policy about all this, if anyone's curious. It's mostly died down, but you can check Deja.

Optical SETI, IMHO, has a much better chance of success, simply because laser "beacons" are much easier to construct, and make detectable, across space than are easily dissipated radio waves.

The laser will spread out, but the pulsed nature of the beam (eek, a pulsed beam) allows for greater power, and the beam still won't spread as much as a radio transmission. A laser's light is all moving in one direction, and starts not only focused, but collimated. Example of spread: a pencil-thick (say.5cm) laser fried from earth is a couple of tens of meters, IIRC, when it reaches the moon. It's still a lot less spread than cube-of-radius (or whatever, i'm tired) for an omnidirectional radio broadcast, especially when taking into account the strength of signal received.

The signal would be designed to technological
level of receiving race they desired.
Could be a relatively simple signal if they want
to reach a lot of races or very sophiscated if
they wanted a high tech level.
Humans would notice patterns in light signals
thousands of years ago; radio only 75 years ago;
and some known physics not yet.

If I was on something like this for a long time and sudden found out that it was a complete waste, becuase of looking in the wrong place, I would be very pissed.

Me, I'd just laugh about it. Welcome to the wonderful world of science, where you can't just flip the card over and look at the answer. Time and effort spent looking is rarely really wasted, even if it eventually turns out there was nothing to find. Pulsed laser beams is just another thing to try. Maybe we should be scanning through gravity waves, too. Who knows? Maybe any lifeform that has any real sense uses controlled quantized subspace variations to communicate over interstellar distances, and they figure no-one else is intelligent enough to talk to yet.

Not unless we figure out how to beat the speed of light. Given an expansion rate of.5c, mankind will have covered only 5,000 light-years of space in 10,000 years. Now, if a supernova were to occur at the centerpoint of human civilization, the last human would be dead of radiation poisoning 7,500 years later....and that's only if they never stopped running.

In the grand scope of things, mankind is merely another bug on the cosmic windshield.

Yeah, using gravity to transmit would be cool, and it could actually be instantaneous (eg, getting rid of that speed of light barrier for communications). The thing is, we don't know whether or not it's instantaneous (gravity could well be limited by the speed of light, or the "speed of gravity". Also, we have no way of transmitting like that right now:P

Are we likely to detect alien races using optical technology? For one thing most lasers are fired down itty bitty pieces of cable, not out to space, and for another, I can hardly imagine being able to detect an alien laser pen at a distance of over 4 light years.

One argument for the unsuccessful detection of radio using aliens has been that this technoly has such a short lifespan in comparison to that of a civilisation e.g. we started using radio about 100 years ago, and we're likely to stop within 30 or so years due to optical technology supplanting it.

The question is what is the likely lifespan of laser technology in the lifespan of a civilisation? How long will it be till we discover something other than coherent light to transmit messages etc ?

Simply because laser radiation is detected, doesn't necessarily mean that an intelligent entity sent it. This article [harvard.edu] from the Goddard Space Flight Center describes natural laser radiation from the atmosphere of Mars (basically a sun-pumped CO2 laser). Similar findings have been observed in comets.

When I saw the title 'looking for aliens in wrong places' I almost expected the article to say 'after spending millions and millions of dollars to search the sky for aliens, first alien was actually found behind the sofa pillows.' And then I thought 'But how would it get there?'

I tend to believe that rate of technological evolution is very much variable. There are two very valid arguments to this...

Beings who exist in a harsh enviroment are forced to devise solutions in order to survive. Because of this need, their technology will develop faster.

Beings in an 'Eden'-type enviroment will evolve technologically faster because energy will not be used to survive. Energy can be used to explore and create.

Myself I tend to believe that the first theory holds more water. Assuming that the survival instinct is as strong in other beings (makes sense) as it is in humans, they will be forced to invent to survive. Beyond basic survival invention tends to snowball, once basic survival is covered you start to want to improve quality of life.

In the second scenario, I don't believe that it encourages technology. I would tend to believe that beings in an enviroment where the beings do not 'need' would not have a desire to invent. Language would certainly flourish, and so would arts. The invention ball would never get rolling, and even though it would be easier for them to advance than the first civilization, they would not.

The one thing that truely strikes me as odd about both the previous search for radio signals and now the search for laser bursts is while "guessing" at what an intelligent and advanced species might use to communicate we ignore the technology on our own world.

Right now we have people researching how to use quantum technology for both instantaneous communication as well as encryption. This technology is hard to evesdrop on in the first place, and if you do you can destroy the message due to the basic laws of quantum physics.

If we "primative" humans are researching this why wouldn't another race elsewhere in the universe be using something similar, or more likely more advanced?

If our species has a significant fraction of its biomass still sitting on this rock in 10,000 years, we DESERVE to get spanked by a passing meteorite/black hole/Vogon construction ship. The only way for a species to surviving planetary scale disasters is to live on more than one planet. Or asteroid. Or interstellar autonomous spacecraft.

Huh? Radio and visible light are the same things. If it's not physically occluded by a planet, laser light will bend around a gravity well just like any other EM source. Radio waves don't travel through large objects (like planets) very well, either. You're right in that a coherent light beam can be more easily blocked by a stellar body than an omnidirectional radio wave, but the odds of either preventing us from talking to aliens are, pardon the pun, astronomical.

You can bet that of people who hear of this project, those who are the equivalent of CB burpers will be waving laser pointers at the Moon and random satellites. If we had megawatt lasers easily available, by now someone would have etched "Hi Mom" across the Moon.

Well, it's no more a waste than using CPU time to animate an aquarium screensaver.

RF searches are most likely to find someone who went through the same logic as us and have broadcast the same type of signal which we're looking for. Detecting leakage is less likely -- look at our broadcasting antenna farms, sending megawatts along horizontal planes to cover the Earth's surface; the Earth's surface is rotating, creating rotating beams which would flicker weakly across receivers every 12/24 Earth hours (plus 3 minutes).

We are most likely to hear dead ETIs. Anyone broadcasting will attract the script kiddies of the Milky Way -- assorted easy-to-create hardware with assorted purposes which is attracted to modulated signals. Any civilization with all its eggs still on its home planet won't survive any space-based intruders.

I mean there is no REAL difference between "radio" and "light" is there? They're both EM particle/waves aren't
they?

Yes, this is absolutely right. They're just different frequencies, different sizes if you will, of the same basic thing. However, you still need different technologies to deal with them: You can't broadcast radio with your flash light, and you can't see anything by the light of a cell phone tower. For a variety of technical reasons, it might be easier for a large civilization to use lasers to communicate instead of radio. Not necessarily easier, just maybe. And so that means it's worth at least taking a look!

For example, lasers are small and can be re-targeted between stars very rapidly. Paul Horowitz has some designs for a setup with moving mirrors which lets you keep your laser stationary but aim its beam at dozens of stars every second. Radio, on the other hand, requires tremendous dish antennae to aim properly, so you can't slew between many stars anywhere near as fast. If you're an alien civilization trying to broadcast to as many targets as you can with limited resources, this might be a good reason to choose the optical over the radio.

As I have said in another post elsewhere, most of these objections are un-founded. The beam of a laser *does* spread out over distances, and it spreads out a heck of a lot when you're dealing with as the tremendous distances between stars. Beyond that, it's actually very easy to broadcast a *wider* beam, in fact easier than sending a narrow beam. Just de-focus the telescope you are using to aim your laser and you can have the beam as wide as you want. It's very, very easy to get a beam easily wide enough to cover an entire solar system at once.

Beyond that, there is no problem about having to calculate the motions of stars over time. We're trying to target close-by stars, which means the travel time is *not* the thousands of years you talk about, but rather only tens or hundreds, which means the stars move hardly at all. Even for more distant stars, note that the galaxy takes a quarter *billion* years to rotate once. Even ten thousand years doesn't move anything all that far. Besides, measuring and tracking the proper motion of stars isn't the computational hassle you seem to think it is. We know the proper motion for thousands of stars, and NASA is working on improving that tenfold with the upcoming SIM mission.

You also seem to think that broadcasts leaking out in all directions are the way to go. THat's not at all clear, because any broadcast spread over the whole sky will necessarily be weak in power. By focusing the beam through a telescope, whether radio or optical, you can get beam powers hundreds of thousands of times brighter than with an omnidirectional transmitter. So even for radio communications, I'll take the extra effort of aiming at different stars for a hundred thousand times stronger signal, thank you very much.

1. Optical communication across interstellar distances is going to suffer from severe extinction (signal absorption
by intervening dust). Even if you can generate a laser pulse brighter than the sun, interstellar extinction is a big
problem to overcome.

Yes, extinction is going to be a consideration. But it's not all that hard to overcome. Look at it this way: If your laser pulse is 100x brigher than your sun on this side of the dust cloud, it's going to be 100x on the other side, too, even if both the sun's light and the star are both reduced by a factor of ten or whatever. They scale together. Anywhere you can see our sun from, and more, you could see our lasers. In fact, if you use a laser on the redder side of things, say even in IR, you're going to have much smaller extinction for your laser than for the star's light, and you'll win out even more in the long run.

Furthermore, radio signals suffer phase shifts and delays due to the intersteller medium. This tends to spread out a signal, originally sent at a narrow wavelength range, into a broader and fainter signal. You don't have this problem with IR or optical lasers, so that's a win for them.

2. A laser beam is very tightly confined, and would have to be aimed very precisely in order to "hit" it's target. The
probabability that the Earth would just happen to cross one of these "lines of communication" is incredibly small.

Wah, major error! Time to go brush up on your optics some more. A laser beam does spread out as it travels, in exactly the same way and at exactly the same rate as radio waves do. Diffraction-limited optics is the same for all frequencies:
S = lambda/D*R
That is, the beam size is proportional to the wavelength, divided by the size of your transmitting telescope, times the distance the beam has traveled. For larger lambda (i.e. radio) you need to use a larger telescope to get as focused a beam - but we do that already, that's why radio telescopes are so much larger than optical ones. Besides which, you neglect the fact that it's *trivially* easy to send as wide a beam we want, just by de-focusing the telescope a little or using a smaller telescope. It's sending narrow beams that's hard! Wide is easy.

The long and the short of it is this: By the time ANY signal, radio, optical, or whatever, has traveled the many lightyears to some other star, the beam will have spread out to be *much* larger than the target solar system. This is true because all forms of light spread out the same way as they travel, and because it's trivial to send as wide a beam as we want just by de-focusing things a bit.

There is no reason to think that mankind will die out any time soon on the cosmic scale. Once we are space-bound we are safe from planetary disasters and even the death of our Sun. Even if we were short-lived, its unlikely that all other civilizations over perhaps billions of years were also short lived. Also, over a timescale of millions of years, our galaxy is pretty small. There have been many calculations about how long it would take for total colonization of all stellar systems within our galaxy. I saw one estimate of about 10 million years for a highly cautious civilisation that spend a lot of time building up new colonies before progressing. Think about that: it means that since the death of the dinosaurs the galaxy could have been colonized 6 times over even with travel way below lightspeed.

Even if most civilizations were content to stay at home, it would only take one that was expansionist, and the galaxy would have been filled with intelligent life (and signs of that life).

I see three possible explanations for the lack of evidence: (1) An elderly civilization is acting as a conservationist and telling all new arrivals to keep quiet and stop expanding. (2) Civilizations have only just started to arise within the past few million years. (3) we are alone.

I don't see how this effects seti@home. The "pulsing light detector" sounds pretty strait forward. If you see a flashing light, you found something now go analize it. With radio there is all kinds of noise so you need a lot of computer power to look for something which you want to study in greater detail, hence seti@home. With this telescope, as soon as you see anything, it is worth studying in greater detail. Think of the logs...

Why bother communicating with the aliens on other planets when we haven't talked to the ones that are already on our planet.

Presumably if they have the technology needed for interstellar travel, they also are well aware of the proper protocols for interstellar comunications. Presumably the method of communication they use exceeds the speed of light (or it at least exceeds c as we perceive it) So using any method based on light or other EM spectrum will likely be fruitless.

My question is how are they different. If a culture can send coherent EM transissions in the visible light range, then why wouldn't then send them in a variety of frequencies including the radio frequencies that SETI is already listening for.

I mean there is no REAL difference between "radio" and "light" is there? They're both EM particle/waves aren't they? (If I'm wrong please correct me, I've never taken a physics class in my life).

I've considered this possibility for a very long time though my idea was that the sun was possibly drowning out all signal that we could potentially capture. I mean really how difficult would it be for some naturally occuring process to interfere with radio broadcasts? I'm sure this has been thought of before but why has it never been brought up?

You are missing the main point, though. The idea is to discover if there is intelligence out there, we'll work on figuring out what they are saying later. SETI is trying to find ANY signal that looks to be artifically created. I'm sure that if we received Alien HDTV signal or the Galactic Quake login prompt, we'd know that it is a sign of intelligence, even if we didn't know how to decode it.

Let's imagine for a minute that the universe is homogeneous. Look at any piece of the universe far enough from its edge, and this piece would look alike from a distance.

In the piece of universe, there would be an equal likelyhood that life starts and evolves into an intelligent lifeform. Step back a little bit. Step back more, so that you see a really big piece of the universe. You would then see many life points located almost uniformly within this big piece. A little bit like when it starts to rain and you see the drops on the ground.

Now, imagine that each of these points is like a balloon expanding (on average) because this intelligent lifeform is colonizing its neighborhood. Well, if it is a dummy intelligent lifeform (like us?), the balloon may never get to expand. Geez, I pushed the button and it nuked everything!

Well, if you wait long enough the balloons eventually touch one another, at which point... you get to meet another extraterrestrial lifeform.

I bet the chances of us seeing someone else is in fact high. You say the rate of evolution would be different, I don't think so. I bet it is about the same everywhere. I think, what happens sometimes is that you don't have enough resources to expand. But, then your neighbor eventually gets to you first, like in Warcraft...

Alright, say 100,000 years. Or 500,000 years. It doesn't matter. Anything less than 10,000,000 years is still a blink of the eye as far as the Universe is concerned.

But his point is more subtle: the chance of another civilization out there that is of comparable technological advancement as ours is practically zero. It's far more likely that they are either way more advanced or are a bunch of cavemen. If they are so much more advanced, then chances are they've known about us for a long time now, so they're ignoring us.

"But there could be millions of worlds out there, each with intelligent life." It doesn't matter - there would still be at least one world that is super-advanced compared to us, and already knows about us and all the other intelligent species out there.--

we stand a better chance of eavesdropping in on cross-chatter, if such a thing exists.

As others have pointed out laser transmissions are good if you want to get ahold of Uncle Nrgnrr'c two star systems over and wish It happy birthday twenty terrestrial years from now... Lasers would be highly efficient assuming there is nothing between you and Nrgnrr'c's receiving station. I suspect for point-to-point communications within our current understanding of physics a laser or laser-like device makes sense. If we are somewhere around the fringe of the transmission we should be able to at least detect it, even if we cannot decode it.

Then again as others have mentioned, if Nrgnrr'c uses some form of communication beyond our current understanding of the universe, say E.T.OL Instant Hypermessenger, then we're S.O.L. until we attain a workable knowledge of the different laws under which it's communications operate.

In my opinion SETI is worth the try -- if we succeed then one of the greatest questions imaginable will be answered. It does not matter whether or not they send us an Encyclopedia Galactica, or if they're in another galaxy, or if they ever even deign to speak with us.

We would know we were not alone.

If we find nothing then we still have an answer. Maybe if a few dozen years from now we've still found nothing then we'll pay a bit closer attention to the special place our noisy little planet holds in this overwhelmingly huge, deeply silent universe. Maybe we'll treat it a little bit better.

Maybe the voices of Earth life will fill the void between the stars several million years from now, and make the universe a less lonely place.

Personally I think humans are far too arrogant in their perception of themselves as somehow superior to Earth's other DNA/RNA carriers. We are not the biggest biomass on the planet. We are not the most numerous species. Other species have had similar impact on the world's climate -- look at the murderous rise of aerobes and imagine the extinctions associated with the sudden permeation of oxygen through an anaerobic biosphere.

For a few years I have held the belief that the perpetuation of DNA/RNA is the driving force of life on Earth. Anything that passes on its DNA is successful in the grand scheme of things. I kind of see Earth as a big colonial organism, sort of like a slime mold. I see humanity as that slime mold's latest attempt to reproduce itself by flinging its spores ever further, even into space itself, and to other worlds.

I suspect that if we should somehow manage to wipe ourselves out (and do so without killing off some of the other more clever species -- some cephalopods, other primates, cetatians) something else will step in a few million years from now and continue the push of perpetuating Terrestrial DNA/RNA.

But I would just as soon have humanity succeed in this venture as to wait a hundred million years for air-breathing octopii to visit other stars.

what does this have to do with seti? yeah, there are plenty of other successful DNA/RNA carriers. plants.... insects.... but they're not going into space...

Me commenting in the wrong area at 2 AM with not enough sleep. Apologies.:)

I think I was agreeing with your idea re: the accuracy of Drake's equation. We basically don't know what direction or form extra-Terrestrial life will take. SETI could be seen as a way of determining the accuracy of Drake's equation.

" it will have to be from a very small cluster of stars near us, which might have been formed near the same time after the big bang, such that planets capable of supporting life would have all started the evolution timer at the same point. "

But how close would depend on the size of the universe, and assuming the universe exists in a vacuum and exploded outward then wouldn't 'life at the same stage' be in a sort of shell (think electron orbits).

Actually, looking for stars about the same age in galaxies about the same age. or in the same 'shell'.

By the way is there any collective noun for galaxies? (don't you dare say universe)

Hey, maybe cosmic rays are some really tightly encoded pulses of information being sent across the universe by other species? Maybe everytime a species figures out how to send out a cosmic ray pulse, they send their response then die out before ever getting a response back, therefore explaining the long periods between cosmic rays! Many species are constantly trying to communicate with each other all the time, they're just dying out before anybody actually can.:)

Project leader Professor Paul Horowitz, of Harvard University, said: "Using only Earth 2001 technology, we could now generate a beamed laser pulse that appears 5,000 times brighter than our sun, as seen by a distant civilisation in the direction of its slender beam.
"In other words, interstellar laser communication is altogether practicable.

So we can communicate by shooting a really strong laser at nearby stars?

First of all, optical SETI is much different than SETI@home, so there wouldn't really have to be a similar distributed computer to do the analysis. All the major signal analysis is done in hardware immediately at the telescope. Basically to search for these signals you need two or three detectors and some simple hardware.

Since the photon emissions from a star are in a random fashion with regard to time, photons from a star usually hit only one of the sensors at a time. The idea is that if a laser pulse was fired at Earth for a few nanoseconds, the detectors would simultaneously receive many photons in the same few nanoseconds, which would be out of the ordinary for normal stars.

The interesting thing about Optical SETI is that you don't necessarily need a massive telescope to do it. Since the HW only cares about multiple photons in the same time frame, it doesn't matter much how precise your telescope is, just how precise your HW and detectors are.

IMO man will never discover alien intelligence in the heavens because he doesn't really want to fidn it. If he did, he wouldn't dismiss the examples right here on earth.

It took 10 years of fighting to get much of the scientific community admit thatour higher ape relatives (chimps, gorillas, and such) possess all the fundemental intellectual capability of about a 5 year old human child. The fight over ape-signing being communication was the focal point of the debate and at the same time the defining exampel of this humanocentric bias.

Even more amazing, wild porpises have shown all the same basic behaviro patterns as humans (including social touchign and recreational sex, as an aside.) There have alsoi beene xperiments with porpises that **stringly** suggest they have their own fairly sophisticated language.

To admit we aren't alone woudl be to admit we aren't unique. That we are just one of countless natural variations on life, no better or worse then any other. This last bit of humano-centricity, that somehow we are "not animals" is a hard thing for many people to accept, even many "objective" scientists.

...doesn't this make sense? I mean, if they're far in advance of us, or even about par, who is to say that they did use or still use radio waves?

We came up with radio for the transmission of sound (at least, if I am wrong about that, don't kill me:) ), and how do we know that every life form would use SOUND as communication?

Also, I hate to say it, but I mean, look at our planet and our people. If YOU were out looking to meet someone, and the first person you ran into was a raving loonie, attacking various parts of his/her own body/pod/gelatinous mass and still mired in the belief in some mystical deities... wouldn't you KEEP looking? Personally, I'd be willing to bet that aliens are out there looking at us like we are the little "challenged" kid down the block, and they are coming up with secret code to keep us from finding them out. And sooner or later they'll be like "Oh shit... they saw us... pretend you didn't notice and run back into your backyard, man... I don't want to hang out with MANKIND. They'll break all our toys."

Room for all scans. We have an over-abundance of computing power to process these signals as is evident with sei@home. Why is searching using radio signals wrong? Once the sensors are built, there are millions of people willing to spend their cycles analyzing your data. I believe there is room for both projects, and many more.

Harvard University, said: "Using only Earth 2001 technology, we could now generate a beamed laser pulse that appears 5,000 times brighter than our sun, as seen by a distant civilisation in the direction of its slender beam.

What will it say? Make Money Fast? Send back a green flash if you want to be removed from our beam-list?

I was reading this short story by Niven (I think it was in N-Space, can't remember the title) that suggested maybe aliens would try to communicate using gravity waves... ('course that's assuming there is a possible way of controlling gravity, like the Tufts Gravity Stone [cwru.edu] thinks there is.) The story suggested Gravity's proogation would be less limited than light, radio, or other Electromagnetic principles.

And by the way... we're listening, but are we transmitting? Is our usual EMF noise enough to clue an alien race in?--

Pretty simple. The only group that could realistically put this together is the government. (Corporations have no incentive to do something on that scale.) Pretend you're a politician. Here's a program that we can spend tons of money on now, but will have absolutely no payoff during your lifetime. Can you say political suicide?

I disagree...with a sufficiently long message, and all other things being equal, it is no more or less difficult to determine how to reconstruct a message from a technical standpoint, whether that message is encoded digitally or in analog. ALL formats are completely arbitrary to someone who has no idea what you are trying to communicate. Consider, for example, analog NTSC television signals....there are many channels of data encoded in a "single channel": horizontal, vertical, color, sound, SAP, frame timing data, and captioning. And there are dozens of neighboring stations in the spectrum. And right next door is FM. And right next to that is cellular, CB, etc. Since a given TV signal is spread all over the place, how do you, a priori, determine where to start hacking the signal up? Which subsignals do you associate with each other?

It is a much more difficult problem when you have NO IDEA where to begin.

Imagine if you will... the leader of the fifth invader force speaking to
the commander in chief...

"They're made out of meat."
"Meat?"
"Meat. They're made out of meat."
"Meat?"
"There's no doubt about it. We picked several from different parts of
the planet, took them aboard our recon vessels, probed them all the way
through. They're completely meat."
"That's impossible. What about the radio signals? The messages to the
stars."
"They use the radio waves to talk, but the signals don't come from them.
The signals come from machines."
"So who made the machines? That's who we want to contact."
"They made the machines. That's what I'm trying to tell you. Meat made
the machines."
"That's ridiculous. How can meat make a machine? You're asking me to
believe in sentient meat."
"I'm not asking you, I'm telling you. These creatures are the only
sentient race in the sector and they're made out of meat."
"Maybe they're like the Orfolei. You know, a carbon-based intelligence
that goes through a meat stage."
"Nope. They're born meat and they die meat. We studied them for several
of their life spans, which didn't take too long. Do you have any idea
the life span of meat?"
"Spare me. Okay, maybe they're only part meat. You know, like the
Weddilei. A meat head with an electron plasma brain inside."
"Nope. We thought of that, since they do have meat heads like the
Weddilei. But I told you, we probed them. They're meat all the way
through."
"No brain?"
"Oh, there is a brain all right. It's just that the brain is made out of
meat!"
"So... what does the thinking?"
"You're not understanding, are you? The brain does the thinking. The
meat."
"Thinking meat! You're asking me to believe in thinking meat!"
"Yes, thinking meat! Conscious meat! Loving meat. Dreaming meat. The
meat is the whole deal! Are you getting the picture?"
"Omigod. You're serious then. They're made out of meat."
"Finally, Yes. They are indeed made out meat. And they've been trying to
get in touch with us for almost a hundred of their years."
"So what does the meat have in mind?"
"First it wants to talk to us. Then I imagine it wants to explore the
universe, contact other sentients, swap ideas and information. The
usual."
"We're supposed to talk to meat?"
"That's the idea. That's the message they're sending out by radio.
'Hello. Anyone out there? Anyone home?' That sort of thing."
"They actually do talk, then. They use words, ideas, concepts?"
"Oh, yes. Except they do it with meat."
"I thought you just told me they used radio."
"They do, but what do you think is on the radio? Meat sounds. You know
how when you slap or flap meat it makes a noise? They talk by flapping
their meat at each other. They can even sing by squirting air through
their meat."
"Omigod. Singing meat. This is altogether too much. So what do you
advise?"
"Officially or unofficially?"
"Both."
"Officially, we are required to contact, welcome, and log in any and all
sentient races or multibeings in the quadrant, without prejudice, fear,
or favor. Unofficially, I advise that we erase the records and forget
the whole thing."
"I was hoping you would say that."
"It seems harsh, but there is a limit. Do we really want to make contact
with meat?"
"I agree one hundred percent. What's there to say?" `Hello, meat. How's
it going?' But will this work? How many planets are we dealing with
here?"
"Just one. They can travel to other planets in special meat containers,
but they can't live on them. And being meat, they only travel through C
space. Which limits them to the speed of light and makes the possibility
of their ever making contact pretty slim. Infinitesimal, in fact."
"So we just pretend there's no one home in the universe."
"That's it."
"Cruel. But you said it yourself, who wants to meet meat? And the ones
who have been aboard our vessels, the ones you have probed? You're sure
they won't remember?"
"They'll be considered crackpots if they do. We went into their heads
and smoothed out their meat so that we're just a dream to them."
"A dream to meat! How strangely appropriate, that we should be meat's
dream."
"And we can mark this sector unoccupied."
"Good. Agreed, officially and unofficially. Case closed. Any others?
Anyone interesting on that side of the galaxy?"
"Yes, a rather shy but sweet hydrogen core cluster intelligence in a
class nine star in G445 zone. Was in contact two galactic rotations ago,
wants to be friendly again."
"They always come around."
"And why not? Imagine how unbearably, how unutterably cold the universe
would be if one were all alone."

Now, correct me if I'm wrong, but isn't the point of laser communication the fact that the signal does not dissipate nearly as much as a regular beam of light? So it goes to argue that we'd never see the signal unless someone was pinging us to see if there was anybody on Ulmach or whatever they call our little stellar system.

However, it also once again emphasises the we need to take a somewhat more proactive approach and not just receive from systems that are possible targets for life, but also send out. After all someone has to be the initiator of conversation, and who's to say there is life out there, but they too are just listening and not sending.

Present: Radio signals? What alien would use radio signals? They'd have better technology than that, right? Use light.
10 years later: What alien would use light? Use quantum particles.
10 years after that: What alien would use quantum particles? Use antimatter.
10 years after that: What alien would use antimatter? Use quark synthesis.

Eventually we're just going to find we should have been searching for bacteria on fallen meteorites.

All one has to do is to check out the Dead Media website [slashdot.org] to get a sense of the huge variety of communication media and technologies that are no longer in use just on our planet alone.

Another element is that some forms of encryptions are designed to make your data look indistinguishable from noise. Granted that in certain situations (such as politics) this is a naturally occuring phenomena. But in any case, this make detection much more difficult.

Think of space aliens trying to decode all of those encrypted transmissions that we might be seeing from HDTV in a few years. it certainly would not show up in the clear.

Now we try to apply this to projects like SETI. We might have any number of very bright "noise" sources that are actually quantum transmitters for the Server planet of the Western Galactic Gamers Conglomerate (or whatever). and because we haven't paid our subscription fee, we do not get in to play the game.

Needless to say, we would have a long time trying to decode the transmission.This is without even hazarding a guess about what galactic politics is like. We could be in a back water that recently got wiped by some sort of war. We could be in some one's nuetral zone. etc etc etc

Project leader Professor Paul Horowitz, of Harvard University, said: "Using only Earth 2001 technology, we could now generate a beamed laser pulse that appears 5,000 times brighter than our sun, as seen by a distant civilisation in the direction of its slender beam.

But the critical point he forgot to mention is that while we could, we don't. What makes us think the aliens will?

Even if they did, laser based communication is likely to be line of sight so any aliens using this technology will be aiming the beams at their detectors. For us to detect the beam either they'd have to miss and hit us accidentally, or we've got to be within the spreading path of the beam behind the target, or we've got to detect it reflected off interstellar dust or something (which would radically reduce it's brightness).

Optical SETI plans to look for messages encoded using a laser... meaning that the message would have to be beamed directly at Earth (even directly at the telescope itself) for it to be seen? Please correct me if I'm wrong, but the laser beam (being unidirectional) would have to be specifically intended for us to before we'd know it was there. At least the radio waves that the original SETI was looking for were omnidirectional (ie: an alien intelligence could have blasted a message to no one in particular and we could have picked it up).

So now we've got plans to look for intelligent life that sent a message directly to us, to a precise location in the cosmos (that wasn't blocked by a star, planet, gas cloud, etc), during a certain period of time, using a given range of the electromagnetic radiation spectrum, and in a format that we could decipher. Ya right. I'm holding my breath for this one.

As communications technology keeps changing, so will our focus on what we should be trying to detect from another civilization.

Maybe other civilizations would realize that if radio is one of the first technologies developed, that they should merely augment what kind of signals they listen for and transmit. Continue broadcasting and listening for the "primitive" radio signals as that is the least common denominator. Something you expect the other side to have in common. Like PI.

It almost makes me think of them sending a signal so complex or a math problem so hard that we can't decode it or solve it. Wouldn't you rather expect a simple puzzle, recognizable to someone who evolved differently? Similar for the kind of signals they might send.

Since radio signals are the "first" signals out there, leading optical signals by at least dozens of years, they are most likely to be detected first. Shouldn't you keep sending them and listening for them? (Even if you start listening for lasers, etc.?)

Finally one last reason, radio signals are probably the only kind of signals that other civilizations are capable of sending legally. Wouldn't their equivalent of the RIAA/MPAA make more advanced forms of communication illegal?

Don't laser beams spread apart, just very slowly? Don't lasers have ratings of divergence that are measured in extremely small angles? I'm no expert on this. I just recall seeing HeNe lasers in Edmund Scientific that had a "divergence" or somesuch measured in some thousanths of a radian or something. Many years ago.

"They believe a technologically advanced race might be more likely to communicate using pulsed laser beams rather than radio.
"

So, are they sayingis that "advanced races" use a high tech version of morse code. This raises a problem. This implies that the signal is in some unknown Base (binary being base 2) and is encoded in some unknown format for transmission, possibly encrypted by default.

So, lets assume for the sake of arguement that we do find pulsating light that shows some form of pattern, there is pretty much no chance we would have any idea what it's saying and we would have no ability to respond. At least with basic radio signals, like TV and Radio, you can easily reverse enginner the signal...assuming thats not encrypted too (I remeber watching a discovery show where the kid who invented the TV was watching RCA's transmissions to see how far along they were, before he went public). Thus we would have a better chance of being able to respond to them, if it's a local (100 Light years) species.

" ALL formats are completely arbitrary to someone who has no idea what you are trying to communicate"

That is totally not true. Radio, the Great Grandfather of the iformation age can be EASILY decoded and played with absolutely no idea how it originated. People have picked up radio in their hearing aids, cavity fillings, and blenders (Speaking of this, an old college friend has a scupture made of metal that picks up a local radio station when it's raining outside) TV formats are really basic because of the limited resources available to transmit and receive it until recently.

Compare this with something live Voice over IP, which has a somewhat arbitrary formatting. Combine this with 1) not knowing the bit depth 2) Not knowing the Base encoding 3) Not knowing the byte order and 4) Not knowing if the signal is encrypted, I think it's suffice to say such a commication would take a LONG time to decipher.

Compare this to, radio. If voice Radio communication is as basic of a device as it is here, then we will IMMEDIATELY have something to work with. TV with some basic reasoning would also yield results quite quickly, since the very inventor of TV (who worked independantly of RCA...It's a good story....)was watching RCA test broadcasts on his TV. We have a starting point. Some morsecode optical transmission is signifcantly more advanced than both TV and Radio and would be significantly more difficult to decipher, anyone trying to phone us probabally wouldn't use it.

This article is quite silly. Laser light communication would be excellent for communicating to a civilization - but only once you knew where they were. The problem with lasers is that they are highly directional. you need to point them in the direction you want to make a broadcast to and then send you're message. This would entail that any aliens sending out a general "hello and welcome to the club" message, or even just the ambient signals of their civilization, would need to have established the exact position of our planet from very far away.

Think about how many stars are visible to the naked eye - hundreds of thousands. Then think about how many are visible through high powered telescopes - millions. now think of the task of analyzing each star to establish to a high degree of accuracy its particular movement so that you can know exactly where it will be in the thousands of years in the future when your signal will actually arrive at it. And even once you'd done that you'd have to broadcast in such a wide area around the stars position such that the signal could be received by any orbiting planets. That's a computational job on a scale many millions of times greater than simply sending out an all points radio broadcast. and radio waves still travel at the same speed as laser light.

Plus with a laser the beam is so narrow that any dark matter ( think planets, large dust / gas clouds ) which might float by in the time between broadcast and receipt, and happen into its path could block the signal or alter its direction in uncalculable ways.

Overall radio is much more efficient for sending out a general "welcome to the sentience club - wanna play the swap ideas game?" type message.

First of all, not to complain or anything, but we still don't know enough about the natural universe to have any clue whether a billionth-of-a-second-long pulse of coherent light is natural or not.

After all, "laser" light is a natural phenomenon we have learned how to produce and control at will. It stands to reason it may be naturally produced without any intelligence. If you apply the same "intelligence has just gotta happen sometime" standard used by Carl Sagan, so coherent light oughta happen spontaneously at least somewhere, sometime.

The only reasonable way to PROVE it isn't natural is to detect an intelligent pattern embedded in it.

So here's my question: If you only pick up a signal a few billionths of a second in duration, just how much data can be fit there to prove intelligence?

If you look at the electromagnetic spectrum, and presume they'll be looking for light somewhere near the visible spectrum (which is a bad idea for transmission efficiency anyway), and assume that you have to modulate the "carrier" frequency to transmit some data, I calculate that you could fit at most several tens of thousand of bits in a pulse that short. That sounds like a lot but it may be hard to fit (or in our case FIND) a lot of meaning in that kind of pulse.

A good light primer can be found here:
http://micro.magnet.fsu.edu/primer/lightandcolor /e lectromagnetic.html

In October, 1989, a Russian news agency reported that scientists claimed to have established that a city in the former Soviet Union had been visited briefly by a spaceship crewed by three feet tall humanoids and a robot.

The whole article is about using a telescope and computers to look for aliens on distant worlds, then at the end we learn that they have been hanging out in Russia all this time!

The Harvard group postulates that we are much more likely to be contacted by aliens via laser, or other tight-beam system, as the narrower beam width would require less power (makes more effiecient use of power). This theory is right on the money--if the aliens are deliberately trying to contact us. Much more likely, however, is that we would pick up extraneous signals intended for their own use. For those who have seen Contact, think about how the otherworlders discovered us--they picked up the first signal we radiated into space with any significant power. We weren't trying to contact anybody, just send TV across the ocean; that the signal was radiated into space was merely a consequence of using radio as the method of transmission. Because radio signals tend to scatter, especially on that older technology, the signal was radiated in all directions, including "up." Detecting that accidental emission, the aliens determined that there was life on our planet. It is less like communication (a deliberate two-way discourse), and more like Signals Intelligence (SIGINT). And (don't all raise your hands at once) who knows who the leader in SIGINT is? The NSA! Odds are, the NSA is going to discover the signal before SETI, NASA, or any others. I don't mean to suggest that they will discover life--in my opinion, that is highly unlikely, simply because those aren't the types of signals NSA looks for--it would likely be chalked up as noise, and they would go back to monitoring Chinese satellite traffic. I am only saying that they would likely be the first to receive (detect) the presence of the signal. It would have to be analyzed in the proper context (enter SETI) to be recognized for what it is. The ultimate dream system for SETI would be to use the Areciebo (sp?) dish, the VLA, etc, as well as NSA's resources, use NSA's signal-detection and -processing systems, then use their own analysis tools. Imagine what a powerful combination that could be!

The point here is that we are far more likely to detect an alien civilization by listening for spurious emissions (SIGINT) than by searching for signals deliberatly aimed at us. In order to detect a laser aimed at us, we would have to examine every star capable of supporting life (same as with SIGINT), but they would also have to aim the signal at us deliberately--that is, they would have to have already detected us and decided to try to contact us. Think about that from their point of view--if you worked for SETI or NASA or others, would you be shining lasers into space to try to communicate with other planets that may or may not have life and may or may not be listening and may or may not even understand what they are looking for? I know I wouldn't, and I'm a supporter of SETI. Realistically, listening for broadcast signals is much more likely to yield results than looking for tight-beam communications.

Incidentally, I didn't bring up the NSA to suggest any sort of conspiracy, just to discuss the equipment differences. And, no, I really don't believe the US Government has been hiding aliens at Roswell for the last 40 years. To almost-quote Dave Barry, it isn't that I don't believe that aliens might have crashed at Roswell, I just don't believe that our government could successfully run a cover-up for that long.

I think it is good for us to be using both radio and optical telescopes as we can learn things about the cosmos besides just alien life. A previous poster to this discussion noted that some quasars and other anomaly were found thru SETI@home, which supports this theory.

What I didn't understand, was why in the world did that article contain the bit about Russian scientists claiming evidence of: three foot tall humanoids and a robot???!!! That had almost nothing to do with the article and was from 1989! I wonder what prompted the writer of the article to throw that in?